We have developed an animal model (rat) susceptible to aflatoxin toxicity, on which we are able to test the effects of various dietary and/or other metabolic factors on tumorigenesis. Oral contraceptives have been shown to affect numerous metabolic processes and to change the requirements for a number of essential nutrients. In addition they may also be involved in the production of hepatic tumors. This study involves biochemical and histological analyses of blood and tissue of female animals treated with both of these agents - aflatoxin and the oral contraceptive, Enovid E, with oral contraceptive given at either the induction or growth phase of the aflatoxin-induced hepatoma.